For electronic components such as printed circuit boards, environmental stress screening, also commonly referred to as “ageing” or “burn-in” is a part of the usual factory quality control process. Despite the use of high-quality components and assembly procedures, the highly complex nature of electronic components subjects them to occasional manufacturing defects and failures during use. Environmental testing, such as testing variations in temperature, voltage, humidity, etc., is often employed as a means to expedite failure occurrence during production testing of electronic components prior to delivery to end-users or as a way to isolate a given failure that has occurred during the manufacturing process or after use in the field. Because of the high costs associated with such defects and failures in terms of manufacturer warranty obligations and end-user down time, typically a manufacturer will use environmental testing as a way to limit the amount of defective circuit boards leaving the factory as new or being returned to the factory as defective. Therefore, this testing is deemed highly important to manufacturers as part of their customer service and support programs.
While many of the environmental testing steps are completely automated, fault isolation procedures require the intervention of a human operator to transfer the electronic component to the testing chamber, to connect the various data and power cables, to set the environmental parameters in order to reproduce the failure conditions, to probe the electronic component to isolate the failure, and to remove the electronic component from the testing chamber following the fault isolation process. These operator-assisted testing procedures usually include many tedious hours of probing fine pitch electronic components which results in considerable eye and neck strain and can increase the incidence of repetitive motion injuries. Intense competition among manufactures strongly motivates the development and implementation of testing procedures that minimize unit-manufacturing costs. Therefore, ergonomic testing devices that can minimize operator injuries and correspondingly reduce overall manufacturing costs are highly desired.
Moreover, in the usual practice, electronic component testing devices have included several cables that must be connected to and disconnected from the component being tested during each test. After tens or hundreds of connect/disconnect cycles, these cables can develop unpredictable failures, such as open circuits, sporadic intermissions and short circuits. These failures may be related to the cyclic mechanical bending of the cables as welt as the tensile stress induced by pulling on the cable to disconnect the electronic component following testing. These types of failures can be very costly to the manufacturer because failed test cables give erroneous quality control test results leading to a high rate of false rejection and unnecessary rework. It is estimated that the situation due to failing cables can cost manufactures millions of dollars per year in unneeded rework expenses. Accordingly, it is desirable to reduce external cabling required to test electronic components.
Additionally, previous methods of environmental fault isolation testing have been very inefficient to the manufacturer. Previous fault isolation chambers have used externally located heating/cooling units connected to the chamber via external duct work, leading to loss of thermal energy and reduced access to the testing chamber. Also, previous testing chambers have used constant wattage frame heaters for external condensation control. Constant wattage frame heaters have numerous disadvantages, such as wasted power, constant heating of the frame leading to possible hazardous burn conditions, and operator attentiveness required for manually switching on and off the heater strips.
In prior environment test chambers without frame heaters, substantial condensation on chamber surfaces may occur when the chambers are operated for extended periods below the ambient dew point. Such condensation can lead to hazardous electrical conditions.
Therefore, it would be advantageous to employ an ergonomic electronic component testing apparatus that limits the amount of operator motion required for full testing of an electronic component, such as a printed circuit board. Additionally, it would be advantageous to provide an electronic component testing apparatus wherein external heating and cooling ducts and electrical wiring are integrated into the testing unit in order to provide a rotatable unit free from external encumbrances.